The present invention relates generally to disc storage systems. More specifically, the present invention relates to an actuator of the type used in disc storage systems.
Disc drives are used to store information, for example magnetically or optically. Disc drives have typically found uses with computer systems to store and retrieve large amounts of data in a fast and efficient manner. There has been an ongoing movement in disc drives to increase drive capacity and the data transfer rates.
A disc drive typically includes at least one disc having a recording surface which rotates about a spindle motor. A transducing head is positioned adjacent the recording surface of the disc and is configured to read and write information on the disc surface. During operation, movement of the disc causes the transducing head to xe2x80x9cflyxe2x80x9d over the disc surface at an extremely small spacing. The transducing head is carried on an actuator assembly which is used to move the transducing head radially relative to the disc surface such that various areas of the disc surface can be accessed. Some actuator assemblies include a bearing cartridge in which a sleeve is configured to rotate relative to a shaft. As recording densities have increased, even a small axial misalignment between the shaft and the sleeve can cause misalignment of the transducing head relative to the disc surface. This can be particularly problematic when rapid movement of the transducing head causes additional force to be applied to the bearing cartridge. This can also make the actuator susceptible to external shocks or vibrations. The bearing cartridge typically includes at least two pairs of races, each carrying ball bearings to allow rotation between the sleeve and the shaft. Misalignment and poor tolerance between the components can lead to errors in positioning the head. Examples of two piece sleeves are shown in, for example, U.S. Pat. Nos. 1,418,888,4,106,827, 4,138,169 and 4,425,009. These references show sleeves which are in butt contact or which require separate raceways for the bearing assemblies.
The present invention provides a solution to this and other problems and offers advantages over the prior art.
The present invention relates to bearing cartridges which have a shaft and a sleeve which solve the above-mentioned problem.
In accordance with one embodiment of the invention, a pivot bearing cartridge for use in an actuator assembly includes a shaft. The shaft includes a first shaft raceway and a second shaft raceway, each extending around a circumference of the shaft. A first outer sleeve extends around the circumference of the shaft and includes a first sleeve raceway generally aligned with the first shaft raceway. A second outer sleeve, coupled to the first sleeve, extends around the circumference of the shaft and includes a second sleeve raceway generally aligned with the second shaft raceway. First ball bearings are provided between the first shaft and first sleeve raceways and second ball bearings are provided between the second shaft and second sleeve raceways.
These and various other features as well as advantages which characterize the present invention will be apparent upon reading of the following detailed description and review of the associate drawings.